An HPLC method for the determination of diastereomeric prodrug RS-79070-004 in human plasma.

Ganciclovir is an antiviral nucleoside analogue approved for treatment and prevention of cytomegalovirus infections in immunocompromised subjects. RS-79070-194, a diastereomeric monovalyl ester of ganciclovir (hydrochloride salt), is under evaluation as a prodrug to increase the bioavailability of ganciclovir. An HPLC method with column switching has been developed and validated for quantification of the corresponding free base RS-79070-004 in human plasma. In the method, proteinaceous material in 0.25 ml of plasma is precipitated by trichloroacetic acid. An aliquot of the supernatant is analyzed by HPLC, with automated column switching to remove late-eluting materials that might interfere with the analyte peaks in subsequent runs. Detection of RS-79070-004 is by UV lambda = 254 nm). The peak areas for each isomer are summed to generate a value for total RS-79070-004. The method has a validated range of 0.0400-4.00 microg/ml and a lower limit of quantification of 0.0400 microg/ml. All intra- and inter-assay %CVs were < 7.5%, and all recoveries (accuracy) were within 6% of nominal values. No interference was observed by ganciclovir, caffeine, acetaminophen, or ibuprofen. Analyte stability in plasma and in the sample extracts is adequate for the specified collection, storage, and analysis conditions. The validated method has been successfully used to analyze clinical study samples.